Comment: Olive green diamond, good in color, but opaque and in a simple local cut (it therefore costs less than 2.4 million dollars :-). A re-cut and re-polish would sharpen its looks if you have the time (free of charge). 6mm round will make for unique ring-stone. Noble, rare, and as durable as it gets. Obviously, a color-gem that would enjoy a halo of brilliant gems to add luster. Small green gems with high dispersion, sphene, demantoid or tsavorite would make a beautiful choice for a halo-ring. Allow us to take care of the details and we will present you with a most pretty jewel.

P.S. Diamonds, as many other gems, can be brightened in tone by a little sunshine, as here below. A little sunshine does us all good, right?